Lipid-associated macrophages reshape BAT cell identity in obesity.

Obesity and type 2 diabetes cause a loss in brown adipose tissue (BAT) activity, but the molecular mechanisms that drive BAT cell remodeling remain largely unexplored. Using a multilayered approach, we comprehensively mapped a reorganization in BAT cells. We uncovered a subset of macrophages as lipid-associated macrophages (LAMs), which were massively increased in genetic and dietary model of BAT expansion. LAMs participate in this scenario by capturing extracellular vesicles carrying damaged lipids and mitochondria released from metabolically stressed brown adipocytes. CD36 scavenger receptor drove LAM phenotype, and CD36-deficient LAMs were able to increase brown fat genes in adipocytes. LAMs released transforming growth factor ß1 (TGF-ß1), which promoted the loss of brown adipocyte identity through aldehyde dehydrogenase 1 family member A1 (Aldh1a1) induction. These findings unfold cell dynamic changes in BAT during obesity and identify LAMs as key responders to tissue metabolic stress and drivers of loss of brown adipocyte identity.

Polyamine metabolism in macrophage-adipose tissue function and homeostasis.

Intracellular metabolism is a crucial regulator of macrophage function. Recent evidence revealed that the polyamine pathway and subsequent hypusination of eukaryotic initiation factor 5A (eIF5A) are master regulators of immune cell functions. In brown adipose tissue (BAT), macrophages show an impressive degree of heterogenicity, with specific subsets supporting adaptive thermogenesis during cold exposure. In this review, we discuss the impact of polyamine metabolism on macrophage diversity and function, with a particular focus on their role in adipose tissue homeostasis. Thus, we highlight the exploration of how polyamine metabolism in macrophages contributes to BAT homeostasis as an attractive and exciting new field of research.

Protocol for detecting mitochondria extracellular vesicles of brown adipose tissue in mice.

Brown adipose tissue (BAT) is mitochondria rich, enabling high oxidative metabolism for non-shivering thermogenesis. The release of large/small extracellular vesicles (EVs) containing mitochondria or mitochondrial fragments, termed mito-EVs, may support mitochondrial quality control or intercellular communication. We present a protocol to isolate and characterize mito-EVs. We detail steps for BAT processing, cell debris removal, differential centrifugation (dC), and mito-EV analysis by flow cytometry and immunoblotting assays. For complete details on the use and execution of this protocol, please refer to Rosina et al.1.

Frataxin deficiency shifts metabolism to promote reactive microglia via glucose catabolism.

Immunometabolism investigates the intricate relationship between the immune system and cellular metabolism. This study delves into the consequences of mitochondrial frataxin (FXN) depletion, the primary cause of Friedreich's ataxia (FRDA), a debilitating neurodegenerative condition characterized by impaired coordination and muscle control. By using single-cell RNA sequencing, we have identified distinct cellular clusters within the cerebellum of an FRDA mouse model, emphasizing a significant loss in the homeostatic response of microglial cells lacking FXN. Remarkably, these microglia deficient in FXN display heightened reactive responses to inflammatory stimuli. Furthermore, our metabolomic analyses reveal a shift towards glycolysis and itaconate production in these cells. Remarkably, treatment with butyrate counteracts these immunometabolic changes, triggering an antioxidant response via the itaconate-Nrf2-GSH pathways and suppressing the expression of inflammatory genes. Furthermore, we identify Hcar2 (GPR109A) as a mediator involved in restoring the homeostasis of microglia without FXN. Motor function tests conducted on FRDA mice underscore the neuroprotective attributes of butyrate supplementation, enhancing neuromotor performance. In conclusion, our findings elucidate the role of disrupted homeostatic function in cerebellar microglia in the pathogenesis of FRDA. Moreover, they underscore the potential of butyrate to mitigate inflammatory gene expression, correct metabolic imbalances, and improve neuromotor capabilities in FRDA.

Soybean Oil-Based 3D Printed Mesh Designed for Guided Bone Regeneration (GBR) in Oral Surgery.

This study aims to obtain a cyto-compatible 3D printable bio-resin for the manufacturing of meshes designed from acquired real patients' bone defect to be used in future for guided bone regeneration (GBR), achieving the goal of personalized medicine, decreasing surgical, recovery time, and patient discomfort. To this purpose, a biobased, biocompatible, and photo-curable resin made of acrylated epoxidized soybean oil (AESO) diluted with soybean oil (SO) is developed and 3D printed using a commercial digital light processing (DLP) 3D printer. 3D printed samples show good thermal properties, allowing for thermally-based sterilization process and mechanical properties typical of crosslinked natural oils (i.e., E = 12 MPa, UTS = 1.5 MPa), suitable for the GBR application in the oral surgery. The AESO-SO bio-resin proves to be cytocompatible, allowing for fibroblast cells proliferation (viability at 72 h > 97%), without inducing severe inflammatory response when co-cultured with macrophages, as demonstrated by cytokine antibody arrays, that is anyway resolved in the first 24 h. Moreover, accelerated degradation tests prove that the bio-resin is biodegradable in hydrolytic environments.

Butyrate prevents visceral adipose tissue inflammation and metabolic alterations in a Friedreich's ataxia mouse model.

Friedreich's ataxia (FA) is a neurodegenerative disease resulting from a mutation in the FXN gene, leading to mitochondrial frataxin deficiency. FA patients exhibit increased visceral adiposity, inflammation, and heightened diabetes risk, negatively affecting prognosis. We investigated visceral white adipose tissue (vWAT) in a murine model (KIKO) to understand its role in FA-related metabolic complications. RNA-seq analysis revealed altered expression of inflammation, angiogenesis, and fibrosis genes. Diabetes-like traits, including larger adipocytes, immune cell infiltration, and increased lactate production, were observed in vWAT. FXN downregulation in cultured adipocytes mirrored vWAT diabetes-like features, showing metabolic shifts toward glycolysis and lactate production. Metagenomic analysis indicated a reduction in fecal butyrate-producing bacteria, known to exert antidiabetic effects. A butyrate-enriched diet restrained vWAT abnormalities and mitigated diabetes features in KIKO mice. Our work emphasizes the role of vWAT in FA-related metabolic issues and suggests butyrate as a safe and promising adjunct for FA management.

Lipocalin-2 promotes adipose-macrophage interactions to shape peripheral and central inflammatory responses in experimental autoimmune encephalomyelitis.

OBJECTIVE: Accumulating evidence suggests that dysfunctional adipose tissue (AT) plays a major role in the risk of developing multiple sclerosis (MS), the most common immune-mediated and demyelinating disease of the central nervous system. However, the contribution of adipose tissue to the etiology and progression of MS is still obscure. This study aimed at deciphering the responses of AT in experimental autoimmune encephalomyelitis (EAE), the best characterized animal model of MS. RESULTS AND METHODS: We observed a significant AT loss in EAE mice at the onset of disease, with a significant infiltration of M1-like macrophages and fibrosis in the AT, resembling a cachectic phenotype. Through an integrative and multilayered approach, we identified lipocalin2 (LCN2) as the key molecule released by dysfunctional adipocytes through redox-dependent mechanism. Adipose-derived LCN2 shapes the pro-inflammatory macrophage phenotype, and the genetic deficiency of LCN2 specifically in AT reduced weight loss as well as inflammatory macrophage infiltration in spinal cord in EAE mice. Mature adipocytes downregulating LCN2 reduced lipolytic response to inflammatory stimuli (e.g. TNFα) through an ATGL-mediated mechanism. CONCLUSIONS: Overall data highlighted a role LCN2 in exacerbating inflammatory phenotype in EAE model, suggesting a pathogenic role of dysfunctional AT in MS.

Multifaceted mitochondrial quality control in brown adipose tissue.

Brown adipose tissue (BAT) controls mammalian core body temperature by non-shivering thermogenesis. BAT is extraordinarily rich in mitochondria, which have the peculiarity of generating heat by uncoupled respiration. Since the mitochondrial activity of BAT is subject to cycles of activation and deactivation in response to environmental temperature changes, an integrated mitochondrial quality control (MQC) system is of fundamental importance to ensure BAT physiology. Here, we provide an overview of the conventional and alternative mechanisms through which thermogenic adipocytes selectively remove damaged parts of mitochondria and how macrophages participate in the MQC system by removing extracellular mitochondrial waste to maintain the thermogenic function of BAT.

Exogenous miRNAs from Moringa oleifera Lam. recover a dysregulated lipid metabolism.

A balanced diet is critical for human health, and edible plants play an important role in providing essential micronutrients as well as specific microRNAs (miRNAs) that can regulate human gene expression. Here we present the effects of Moringa oleifera (MO) miRNAs (mol-miRs) on lipid metabolism. Through in silico studies we identified the potential genes involved in lipid metabolism targeted by mol-miRs. To this end, we tested the efficacy of an aqueous extract of MO seeds (MOES), as suggested in traditional African ethnomedicine, or its purified miRNAs. The biological properties of MO preparations were investigated using a human derived hepatoma cell line (HepG2) as a model. MOES treatment decreased intracellular lipid accumulation and induced apoptosis in HepG2. In the same cell line, transfection with mol-miRs showed similar effects to MOES. Moreover, the effect of the mol-miR pool was investigated in a pre-obese mouse model, in which treatment with mol-miRs was able to prevent dysregulation of lipid metabolism.

MicroRNAs, Long Non-Coding RNAs, and Circular RNAs in the Redox Control of Cell Senescence.

Cell senescence is critical in diverse aspects of organism life. It is involved in tissue development and homeostasis, as well as in tumor suppression. Consequently, it is tightly integrated with basic physiological processes during life. On the other hand, senescence is gradually being considered as a major contributor of organismal aging and age-related diseases. Increased oxidative stress is one of the main risk factors for cellular damages, and thus a driver of senescence. In fact, there is an intimate link between cell senescence and response to different types of cellular stress. Oxidative stress occurs when the production of reactive oxygen species/reactive nitrogen species (ROS/RNS) is not adequately detoxified by the antioxidant defense systems. Non-coding RNAs are endogenous transcripts that govern gene regulatory networks, thus impacting both physiological and pathological events. Among these molecules, microRNAs, long non-coding RNAs, and more recently circular RNAs are considered crucial mediators of almost all cellular processes, including those implicated in oxidative stress responses. Here, we will describe recent data on the link between ROS/RNS-induced senescence and the current knowledge on the role of non-coding RNAs in the senescence program.

Ejection of damaged mitochondria and their removal by macrophages ensure efficient thermogenesis in brown adipose tissue.

Recent findings have demonstrated that mitochondria can be transferred between cells to control metabolic homeostasis. Although the mitochondria of brown adipocytes comprise a large component of the cell volume and undergo reorganization to sustain thermogenesis, it remains unclear whether an intercellular mitochondrial transfer occurs in brown adipose tissue (BAT) and regulates adaptive thermogenesis. Herein, we demonstrated that thermogenically stressed brown adipocytes release extracellular vesicles (EVs) that contain oxidatively damaged mitochondrial parts to avoid failure of the thermogenic program. When re-uptaken by parental brown adipocytes, mitochondria-derived EVs reduced peroxisome proliferator-activated receptor-γ signaling and the levels of mitochondrial proteins, including UCP1. Their removal via the phagocytic activity of BAT-resident macrophages is instrumental in preserving BAT physiology. Depletion of macrophages in vivo causes the abnormal accumulation of extracellular mitochondrial vesicles in BAT, impairing the thermogenic response to cold exposure. These findings reveal a homeostatic role of tissue-resident macrophages in the mitochondrial quality control of BAT.

Revisited role of TRAF2 and TRAF2 C-terminal domain in endoplasmic reticulum stress-induced autophagy in HAP1 leukemia cells.

The scaffold protein Tumor Necrosis Factor Receptor-Associated Factor 2 (TRAF2) has been reported to play a key role in the endoplasmic reticulum (ER) stress-induced activation of c-Jun N-terminal Kinase (JNK) and hence autophagy. Autophagy is a highly conserved catabolic process, whose dysregulation is involved in the pathogenesis of various human diseases, including cancer. We investigated the involvement of TRAF2 in autophagy regulation in the human leukemic HAP1 cell line, under both basal and ER stress conditions. In TRAF2-knockout HAP1 cell line (KO), the basal autophagic flux was higher than in the parental cell line (WT). Moreover, tunicamycin-induced ER stress stimulated JNK activation and autophagy both in WT and KO HAP1. On the other hand, re-expression of a TRAF2 C-terminal fragment (residues ,310-501), in a TRAF2-KO cellular background, rendered HAP1 cells unable to activate both JNK and autophagy upon ER stress induction. Of note, this apparent dominant negative effect of the C-terminal fragment was observed even in the absence of the endogenous, full-length TRAF2 molecule. Furthermore, the expression of the C-terminal fragment resulted in both protein kinase B (AKT) pathway activation and increased resistance to the toxic effects induced by prolonged ER stress conditions. These findings indicate that TRAF2 is dispensable for the activation of both JNK and autophagy in HAP1 cells, while the TRAF2 C-terminal domain may play an autonomous role in regulating the cellular response to ER stress.

The Role of Glutathione-S Transferase in Psoriasis and Associated Comorbidities and the Effect of Dimethyl Fumarate in This Pathway.

Psoriasis vulgaris is a chronic inflammatory skin disease characterized by well-demarcated scaly plaques. Oxidative stress plays a crucial role in the psoriasis pathogenesis and is associated with the disease severity. Dimethyl fumarate modulates the activity of the pro-inflammatory transcription factors. This is responsible for the downregulation of inflammatory cytokines and an overall shift from a pro-inflammatory to an anti-inflammatory/regulatory response. Both steps are necessary for the amelioration of psoriatic inflammation, although additional mechanisms have been proposed. Several studies reported a long-term effectiveness and safety of dimethyl fumarate monotherapy in patients with moderate-to-severe psoriasis. Furthermore, psoriasis is a chronic disease often associated to metabolic comorbidities, as obesity, diabetes, and cardiovascular diseases, in which glutathione-S transferase deregulation is present. Glutathione-S transferase is involved in the antioxidant system. An increase of its activity in psoriatic epidermis in comparison with the uninvolved and normal epidermal biopsies has been reported. Dimethyl fumarate depletes glutathione-S transferase by formation of covalently linked conjugates. This review investigates the anti-inflammatory role of dimethyl fumarate in oxidative stress and its effect by reducing oxidative stress. The glutathione-S transferase regulation is helpful in treating psoriasis, with an anti-inflammatory effect on the keratinocytes hyperproliferation, and in modulation of metabolic comorbidities.

Low Sulfur Amino Acid, High Polyunsaturated Fatty Acid Diet Inhibits Breast Cancer Growth.

Cancer cells may acquire resistance to stress signals and reprogram metabolism to meet the energetic demands to support their high proliferation rate and avoid death. Hence, targeting nutrient dependencies of cancer cells has been suggested as a promising anti-cancer strategy. We explored the possibility of killing breast cancer (BC) cells by modifying nutrient availability. We used in vitro models of BC (MCF7 and MDA-MB-231) that were maintained with a low amount of sulfur amino acids (SAAs) and a high amount of oxidizable polyunsatured fatty acids (PUFAs). Treatment with anti-apoptotic, anti-ferroptotic and antioxidant drugs were used to determine the modality of cell death. We reproduced these conditions in vivo by feeding BC-bearing mice with a diet poor in proteins and SAAs and rich in PUFAs (LSAA/HPUFA). Western blot analysis, qPCR and histological analyses were used to assess the anti-cancer effects and the molecular pathways involved. We found that BC cells underwent oxidative damage to DNA and proteins and both apoptosis and ferroptosis were induced. Along with caspases-mediated PARP1 cleavage, we found a lowering of the GSH-GPX4 system and an increase of lipid peroxides. A LSAA/HPUFA diet reduced tumor mass and its vascularization and immune cell infiltration, and induced apoptosis and ferroptotic hallmarks. Furthermore, mitochondrial mass was found to be increased, and the buffering of mitochondrial reactive oxygen species limited GPX4 reduction and DNA damage. Our results suggest that administration of custom diets, targeting the dependency of cancer cells on certain nutrients, can represent a promising complementary option for anti-cancer therapy.

Molecular and histological traits of reduced lysosomal acid lipase activity in the fatty liver.

Recent studies demonstrated reduced blood lysosomal acid lipase (LAL) activity in patients with nonalcoholic fatty liver disease (NAFLD). We aimed to verify hepatic LAL protein content and activity in in vitro and in vivo models of fat overload and in NAFLD patients. LAL protein content and activity were firstly evaluated in Huh7 cells exposed to high-glucose/high-lipid (HGHL) medium and in the liver of C57BL/6 mice fed with high-fat diet (HFD) for 4 and 8 months. LAL protein was also evaluated by immunohistochemistry in liver biopsies from 87 NAFLD patients and 10 controls, and correlated with hepatic histology. Huh7 cells treated with HGHL medium showed a significant reduction of LAL activity, which was consistent with reduced LAL protein levels by western blotting using an antibody towards the N-term of the enzyme. Conversely, antibodies towards the C-term of the enzyme evidenced LAL accumulation, suggesting a post-translational modification that masks the LAL N-term epitope and affects enzymatic activity. Indeed, we found a high rate of ubiquitination and extra-lysosomal localization of LAL protein in cells treated with HGHL medium. Consistent with these findings, inhibition of proteasome triggered dysfunctional LAL accumulation and affected LAL activity. Accumulation of ubiquitinated/dysfunctional LAL was also found in the liver of HFD fed mice. In NAFLD patients, hepatic levels of non-ubiquitinated/functional LAL were lower than in controls and inversely correlated with disease activity and some of the hallmarks of reduced LAL. Fat overload leads to LAL ubiquitination and impairs its function, possibly reducing hepatic fat disposal and promoting NAFLD activity.

The Nrf2 induction prevents ferroptosis in Friedreich's Ataxia.

Ferroptosis is an iron-dependent cell death caused by impaired glutathione metabolism, lipid peroxidation and mitochondrial failure. Emerging evidences report a role for ferroptosis in Friedreich's Ataxia (FRDA), a neurodegenerative disease caused by the decreased expression of the mitochondrial protein frataxin. Nrf2 signalling is implicated in many molecular aspects of ferroptosis, by upstream regulating glutathione homeostasis, mitochondrial function and lipid metabolism. As Nrf2 is down-regulated in FRDA, targeting Nrf2-mediated ferroptosis in FRDA may be an attractive option to counteract neurodegeneration in such disease, thus paving the way to new therapeutic opportunities. In this study, we evaluated ferroptosis hallmarks in frataxin-silenced mouse myoblasts, in hearts of a frataxin Knockin/Knockout (KIKO) mouse model, in skin fibroblasts and blood of patients, particularly focusing on ferroptosis-driven gene expression, mitochondrial impairment and lipid peroxidation. The efficacy of Nrf2 inducers to neutralize ferroptosis has been also evaluated.

An Overview of the Ferroptosis Hallmarks in Friedreich's Ataxia.

BACKGROUND: Friedreich's ataxia (FRDA) is a neurodegenerative disease characterized by early mortality due to hypertrophic cardiomyopathy. FRDA is caused by reduced levels of frataxin (FXN), a mitochondrial protein involved in the synthesis of iron-sulphur clusters, leading to iron accumulation at the mitochondrial level, uncontrolled production of reactive oxygen species and lipid peroxidation. These features are also common to ferroptosis, an iron-mediated type of cell death triggered by accumulation of lipoperoxides with distinct morphological and molecular characteristics with respect to other known cell deaths. SCOPE OF REVIEW: Even though ferroptosis has been associated with various neurodegenerative diseases including FRDA, the mechanisms leading to disease onset/progression have not been demonstrated yet. We describe the molecular alterations occurring in FRDA that overlap with those characterizing ferroptosis. MAJOR CONCLUSIONS: The study of ferroptotic pathways is necessary for the understanding of FRDA pathogenesis, and anti-ferroptotic drugs could be envisaged as therapeutic strategies to cure FRDA.